Circuit breaker

ABSTRACT

A miniature remote control circuit breaker in which a movable contact member including a movable contact is engageable with a fixed contact. Motor means, such as a solenoid and an armature actuated thereby, move the contact member from a contacts-open position to a contacts-closed position when the solenoid is energized by remote switch means. Preferably a linkage including two resiliently connected driving members is employed to couple the motor means to the contact member. Condition-sensing (e.g., current-sensing) latch means retain the contact member in its contacts-closed position until the condition sensed varies beyond a predetermined value whereupon the latch means releases the contact member, thereby opening the contacts independently of the energization of the motor means. Further latch means are provided to retain the contact member in its closed position. The latter latch means are responsive to further actuation of the remote switch means thereby to release the contact member and separate said contacts. A further solenoid and armature are preferably provided to effect the release of the further latch means in response to further actuation of the remote switch means.

United States Patent Cooper et al.

[151 3,651,436 1451 Mar. 21, 1972 [54] CIRCUIT BREAKER [72] Inventors:Lawrence E. Cooper; Robert W. Peterson,

' both of Attleboro, Mass.

[73] Assignee: Texas Instruments Incorporated, Dallas,

Tex.

22 Filed: Jan. 2, 1970 [2]] Appl. No.: 479

[52] U.S.Cl. ..335/13 [51] 1nt.Cl. ..H0lh 77/06 [58] FieldoiSearch..335/13,38,43, 15, 19, 73, 335/174, 177

[56] References Cited UNITED STATES PATENTS 2,387,373 10/1945 Watkins etal. ..335/19 2,551,303 5/1951 Theunissen ..335/38 2,821,586 1/1958 Bohn..335/13 2,870,289 1/1959 Kyle, Jr ..335/13 3,072,765 1/1963 l-lauser etal. .....335/38 3,332,044 1/1967 Camp et al... .....335/73 3,366,900l/l968 Barkan ..335/15 Primary Examiner-Harold Broome Attorney-HaroldLevine, Edward J. Connors, Jr., John A. Haug, James P. McAndrews andGerald B. Epstein [57] ABSTRACT A miniature remote control circuitbreaker in which a movable contact member including a movable contact isengageable with a fixed contact. Motor means, such as a solenoid and anarmature actuated thereby, move the contact member from a contacts-openposition to a contacts-closed position when the solenoid is energized byremote switch means. Preferably a linkage including two resilientlyconnected driving members is employed to couple the motor means to thecontact member. Condition-sensing (e.g., current-sensing) latch meansretain the contact member in its contacts-closed position until thecondition sensed varies beyond a predetermined value whereupon the latchmeans releases the contact member, thereby opening the contactsindependently of the energization of the motor means. Further latchmeans are provided to retain the contact member in its closed position.The latter latch means are responsive to further actuation of the remoteswitch means thereby to release the contact member and separate saidcontacts. A further solenoid and armature are preferably provided toeffect the release of the further latch means in response to furtheractuation of the remote switch means.

FCBI

16 Claims, 14 Drawing Figures lllh.

will

PATENTEDMARM m2 SHEET 1 [IF 7 NQE PATENTEUMARZI I972 SHEET 2 [IF 7 WCBIFIG. 3

PATENTEUMARZI 1922 V 3,651,436 SHEET OF 7 FIGS CB l K HI I PATENTEDMARZI1972 SHEET 6 BF 7 Fla CIRCUIT BREAKER This invention relates to circuitbreakers and more particularly to remotely controlled circuit breakers.

With the advent of the larger jet aircraft and their increasedelectrical power requirements, the weight and cost of the larger loopruns of heavy expensive aviation cable between the power generators andelectrical loads via the flight engineers console or cockpit becomeexcessive. A large portion of this cable expense and weight can beeliminated by reducing the lengths of the power lead runs. This can beeffectively accomplished by the use of remotely controlled circuitbreakers located near the generator with small remote control unitspositioned in the cockpit and interconnected with the breaker itself bylight inexpensive control wires, thus permitting much shorter and directpower lead runs between the generator gear and the loads. A typicaljumbo jet may require over one thousand circuit breakers, many of whichadvantageously could be the remote control type. These remote controlbreakers should not only function reliably to protect against overloads(both of the short-circuit and low level or ultimate trip types), butshould also function as contactors which are resettable and trippablefrom the remote control unit. Existing remote control circuit breakers,however, have various disadvantages. Some lack any means for remotelyindicating when the breaker has tripped due to an overload, or fail toprovide for both tripping as well as resetting the breaker from theremote control unit, or do not protect a load from both short circuitand ultimate trip or low level overloads. Others do not have or fail toretain close tolerances as to tripping levels, and are subject to otherdifficulties. The remotely controlled circuit breakers of this inventionovercome these disadvantages and provide numerous significantadvantageous features.

Among the several objects of this invention may be noted the provisionof remotely controlled circuit breakers which permit substantialeconomies in the reduction of cable weight and expense; the provision ofsuch breakers in which power switching, overload sensing and theprotection functions are provided in one unit located in a positionclose to the power source and the load being supplied and protected,while even smaller remote units are positioned in the strategic andspatially limited area of the cockpit or flight engineers console, thereto provide the control or on-off signalling functions and to indicateoverload conditions; the provision of breakers of the type describedwhich combine contactor and breaker functions in one package, protectagainst all types of overloads, and are inherently trip-free; theprovision of remote control circuit breakers which protect the circuitsregardless of the condition of the remote control unit and circuitry andare independently fail-safe even in the event of failure of controlvoltage; the provision of such breakers which may be of the latch-in ornon-latch types and which comprise substantially the same componentswith only minor modification; the provision of circuit breakers whichhave and retain close tolerances as to tripping levels and providespecific and substantially constant contact pressure and calibration,which are maintained throughout the life of the breaker; and theprovision of such remote control circuit breakers having minimal numberof control wires and which are compact, light in weight, reliable inoperation, will handle a wide variety of AC and DC voltage and currentrequirements, and have a long operating life. Other objects and featureswill be in part apparent and in part pointed out hereinafter.

Briefly,-a remote control circuit breaker of this invention includes afixed contact and a movable contact member having a movable contactengageable with the fixed contact, and being movable between a first orcontacts-open position and a second or contacts-closed position. Motormeans are provided for moving the contact member from its first positionto its second position when the motor means is actuated by means remotefrom the circuit breaker. The contact member is retained in its secondposition by condition-sensing latch means until the condition sensedvaries beyond'a predetermined value whereupon this latch means releasesthe contact member to open said contacts independently of the actuationof the motor means. Further latch means are utilized to retain thecontact member in its second position. These further latch means areresponsive to actuation of the remote means thereby to release saidcontact member and separate said contacts.

The invention accordingly comprises the constructions hereinafterdescribed, the scope of the invention being indicated in the followingclaims.

In the accompanying drawings, in which several of various possibleembodiments of the invention are illustrated,

FIGS. 1 and 2 are schematic and diagrammatic representations of tworemote control circuit breaker embodiments of the invention;

FIGS. 3-5 are elevations of the circuit breaker represented in FIG. 1,parts being broken away, illustrating, respectively, the components in anormal contacts-open, a normal contactsclosed and a trip-freeconfiguration or position.

FIG. 6 is an elevation of the circuit breaker represented in FIG. 2,parts being broken away;

FIG. 7 is a detail view of a contact member component taken generally online 9-9 of FIG. 3 with parts broken away;

FIG. 8 is a detail view of a latch member component taken generally online 8-8 of FIG. 3 with parts broken away;

FIG. 9 is an elevation of another breaker embodiment of this inventionincluding a manually operable arrangement to move the breaker contactmember between its closed and open positions;

FIGS. l0A-C are elevations of three component slider plates of a sliderassembly of a circuit breaker of this invention;and

FIGS. 11A and B are edge elevations of the slider assembly in its twopositions.

Corresponding reference characters indicate corresponding partsthroughout the several views of the drawings.

Referring now to the drawings, and more particularly to FIG. 1, a remotecontrol unit, indicated generally at RC1, is shown connected by a singleconductor 1 to a circuit breaker CB1. Remote control RC1 includes acircuit breaker device 3 of the bimetal thermostatic type including anauxiliary set of contacts 5 commonly operated by a push button PBl. Uponactuation of FBI to the left as shown in FIG. 1, the main contacts ofdevice 3 are bridged by the breakers bimetallic element 7 and auxiliarycontacts 5 are opened. A load control switch S1 is optionally providedto connect conductor 1 to the positive side of a control voltage sourcerepresented as +V (the negative side of which is grounded) viabimetallic element 7 when push button FBI is actuated to open contacts 5and element 7 is bridging the main contacts of breaker 3. Control switchS1, when actuated or moved to its alternate position, grounds conductor1.

Breaker 3 may be any conventional bimetal type breaker preferably havinga low current rating, e.g., on the order of amp. When its rated currentcarrying capacity is exceeded, its

bimetal element 7 will reverse its curvature and cause push button FBIto pop outwardly (to the right as shown in FIG. 1) thus serving toindicate, as will be described hereinafter, when main breaker CB1 istripped because of an overload. It will be understood that otherconductor means, such as an electromagnetic type or a light, may be usedto provide an indication at the remote control unit RC1 of overloadtripping of CB1.

Breaker CB1 includes two terminals T1 and T2 which are connected inseries with a power lead or conductor interconnecting a source ofelectric power to an electrical load. The current path from T1 to T2includes a current-sensing latch means LMl having an electromagnet 9 anda U-shaped bimetal element 11, a flexible braid lead 13 and a contactmember or arm 15 carrying a movable main contact 17 and a movable arcingcontact 19 which respectively conductively engage a fixed main contact21 and a fixed arcing contact 23. Latch means LMI also includes apivotable latch member 25 pivoted about a pin 27 and having an abutmentor catch 29 and an upper end 31 adapted to be contacted and moved to theright by the upper end of bimetal element 11 when the latter is heatedby current exceeding the breakers rating. Contact member 15 has an end33 supported on catch 29 which constitutes a pivot for contact member 15when the latter is actuated by a linkage 35 to move the fixed andmovable contacts thereof into conductive engagement. Contact member 15is urged or biased toward its contacts-open position by a spring asrepresented at 37. Linkage 35 is actuatable by an armature 39 of a resetsolenoid RS. Coacting with linkage 35 is a further latch means LM2which, when linkage 35 is actuated to move contact member 15 to itsclosed position, will engage linkage 35 and retain contact member 15 inits contacts-closed condition. A spring represented at 41 biases a latcharm 43 of LM2 against the linkage for retention thereof. Latch arm 43 isactuatable by a trip solenoid TS which when energized retracts arm 43 torelease the linkage 35 and permit the contact member to return to itscontacts-open position.

When PB1 is in its closed position with bimetal element 7 bridging themain contacts of breaker 3 and switch S1 is in the position illustrated,a circuit energizing reset solenoid R5 is completed through one set ofcontacts of a double-throw single-pole mode or latch switch LS, therebydriving contact member 15 downwardly into its closed position throughlinkage 35. This action moves switch LS to its other mode wherein itconnects solenoid TS to conductor 1 which is at potential +V. As theother terminal of TS is also connected to +V, it will remain deenergizeduntil further actuation of the breaker 3 or switch S1. If a fault oroverload condition occurs, the overcurrent condition will cause latchmember 25 of latch means LMl to pivot clockwise and release the end 33of contact member 15, thus permitting the contacts to open under thebias of spring 37. As contact member end 33 moves clockwise it actuatesa trip or overload switch OS, causing it to close and ground conductor 1through an optional resistor 45. The current then drawn through bimetal7 will cause it to heat and pop open, actuating FBI to indicate at theremote control unit RC1 that an overload condition has tripped breakerCB1. Tripping of remote control RC1 energize trip solenoid TS whichdisengages arm 43 of LM2 to release the linkage 35 and permit thecontact member to return to its contacts-open position.

Breaker CB1 may be operated as a contactor from RC1 by either movingload control switch S1 to its opposite position or manually moving FBIto the position illustrated in FIG. 1, thereby to trip breaker CB1 froma remote position. Either action connects conductor 1 to ground and asthe other terminal of trip solenoid TS is connected to +V, TS isenergized via the contacts of latch switch LS thereby firing orenergizing TS to release latch .means LM2 and permit contact member 15to move to its contacts-open position. In this mode of operation thecurrent-sensing thermally responsive latch means LMl are not actuatedand the end 33 of contact member 15 pivots on abutment 29. Thus theoverload switch OS is not actuated in this contactor-trip mode ofactuation. Resetting of breaker CB1 after tripping is accomplished byactuation of the remote unit RC1 as described above, so as to energizeor fire reset solenoid RS. If tripping is due to an overload, CB1 willbe tripfree, i.e., as long as bimetal element 11 remains hot, latchmember 25 will be moved to the right and contact member end 33 will haveno available point on which to pivot.

If loss of control power or an open circuit occurs on the control line,contact member 15 of breaker CB1 will not change its position sinceneither the trip nor reset solenoids TS and RS can then be energized.Also, if control conductor 1 is grounded when the contact member 15 ofbreaker CB1 is in its open position, both terminals of solenoid RS areat ground potential and it will not fire, so that CB1 cannot be resetunder this condition. If control member 15 is closed and conductor 1becomes grounded, trip solenoid TS will be tired, opening breaker CB1and PB! will be actuated by bimetal element 7.

It is to be noted that load control switch S1 is optionally provided tominimize wear on breaker 3. If the latter is used not only for resettingafter overload trips but also for all operations in the contactor mode,this breaker would have to have a useful life of many tens of thousandsof operating cycles. By using S1 in this contactor mode of operation andbuilding breaker 3 to last several thousands of cycles, switch S1 can bemore economically designed to have a reliable life of many tens ofthousands of operational cycles, and provide a remote control unit withincreased overall reliability and operating life but at a decreasedcost.

The FIG. 1 remote control circuit breaker system is of the latch-intype, i.e., during normal operation the contact member 15 is latched inits contacts-closed position with reset solenoid RS being deenergized.One or the other of latch means LMl or LM2 must be actuated to open thecontacts,

the latter by energization of trip solenoid TS to overcome the latchingbias of spring 41. In such a latch-in system, failure of thecontrol'po'wer or interruption thereof will not trip breaker CB1. Insome instances it is desirable to provide a nonlatch type operation,i.e., the contact arm or member is held closed by a latch means which ismaintained energized so that upon any interruption of control power thebreaker automatically opens and must be reset to reclose. This typeoperation is conveniently accomplished in accordance with this inventionwith only minor modification of a few components of breaker CB1 and unitRC1. A nonlatch system is illustrated in FIG. 2, by utilizing a remotecontrol unit RC2 which employs a breaker 3' (which is identical tobreaker 3 but includes no auxiliary contacts) and a single-polesingle-throw load control switch S1 rather than a double-throw switchS1. A circuit breaker CB2 is utilized instead of breaker CB1, the formerhaving a single-pole single-throw latch switch LS and modified latchmeans LM2, trip solenoid TS and biasing spring 41'. To close or resetcontact member 15, load control switch S1 or breaker 3 is operated toapply +V control voltage to reset solenoid RS. However, in this nonlatchsystem of FIG. 2, the trip solenoid TS is concurrently energized to urgelatch arm 43 into engagement with linkage 35 so as to maintain it in itsclosed position when it reaches that position. As latch arm 43 islightly biased out of latching engagement by a spring 41', any loss orinterruption of control power will cause latch means LM2 to releaselinkage 35 and open the contacts. Operation of this nonlatch system ofFIG. 2 upon overload is essentially the same as describedabove in regardto the latchin system of FIG.,1. That is, overload switch OS is actuatedmomentarily by contact member 15 moving into its trip-free I position asabutment 29 is moved out from under end 33 of contact member 15 therebyapplying the control voltage across bimetal element 7 andresistor 45,the controlled short circuit constituted thereby causing a relativelyhigh current flow therethrough, thus causing breaker 3 to operate andindicating at remote control unit RC2 that breaker CB2 has tripped dueto an overload. The opening of breaker 3' opens the circuit throughbimetal element 7 and the automatic release of linkage 35 by latch meansLM2 permits load or mode transfer switch LS to reelose thus preparingthe reset and trip solenoids for subsequent retiring to reset breakerCB2.

It is to be noted that in both the latch-in and nonlatch systems ofFIGS. 1 and 2, latch means LMl operates to cause contact member 15 tomove to an open position while linkage 35 remains in its latched oractuated position. Thus, the circuit protective function of CB1 and CB2is maintained independently of loss of control power or malfunctions onthe control line. Any load fault will cause latch means LMl to tripbreaker CB1 or CB2 and clear the fault.

Referring now'more particularly to FIGS. 3-5, the detailed structure ofan exemplary circuit breaker CB1 is illustrated in its respective threemodes or conditions, viz, open, closed and trip-free. Breaker CB1 isassembled in a housing H molded of suitable plastic or synthetic resininsulating material with appropriate recesses and the like for retainingand mounting components of the breaker mechanism described hereinafter.Terminal T1 is formed integrally with a base portion 45 having a zig-zagextension 47 and an upper portion 49 on which is mounted U-shapedbimetal element 11. Projecting through openings in extension 47 are apair of insulated poles 51 which, together with the conductive turn orturns constituted by the zig-zag configuration of 47, comprise anelectromagnet which includes in its magnetic circuit the pivoted latchmember 25. Latch member 25 includes an arm portion 53 which ispreferably constructed of a bimetal laminate to provide ambienttemperature compensation. The distal end 31 of arm 53 is adapted to beengaged by an extension 55 of bimetal element 11. An eye 57 is providedin the top of latch member 25 for attachment of one end of a spring 59,the other end of which is anchored to a pin 61 mounted in the body ofhousing l-I. Spring 59 exertsa biasing action on latch member 25,tending to hold it in the position shown and resisting pivoting actionaround pivot pin 27, also joumaled or mounted in housing l-I. Thusabutment or catch 29 is normally held in a position adapted to beengaged by a finger 63 secured at end 33 of contact member 15. Braid 13flexibly electrically interconnects the free end of bimetal element 11to contact member 15 at 65. Contact member 15 includes a main armportion 15a to which is secured the movable main contact 17 and ratherflexible resilient auxiliary arm portion 15b carrying movable arcingcontact 19. Portion 15b is slotted to provide an opening 67 throughwhich main contact 17 projects. Secured by welding or the like to a base69 integrally formed with terminal T2 is a stepped contact assembly, thehigher portion constituting the fixed or stationary contact 21, thelower portion being the fixed arcing contact 23. Auxiliary branch or arm15b flexes, as illustrated in FIG. 4, to permit firm conductiveengagement between mating pairs of main and arcing contacts, the latterleading the former as member 15 moves into its closed-contact position(FIG. 4) and trailing it as member 15 moves back to its open-contactposition (FIG. 3). This action protects the main contacts from thearcing action, concentrating this at the arcing contacts to insure thatgood electrical conductivity will be maintained between contact member15 and terminal T2 which is secured to housing H.

Contact member 15 includes a C-shaped bracket 150 having a cross slot 71in its upper reach and an eye 73 in its forward reach. One end of spring37 is attached to bracket 150 at eye 73 and the other end of spring 37is anchored to a pin 75 mounted in housing H, thus biasing contactmember 15 to move clockwise. Bracket 150 has an opening 76 at the kneejuncture of the upper and front reaches thereof so as to provide forunobstructed passage and movement of spring 37. Linkage 35, whichcomprises a slider assembly including three slider plates 35a, 35b, 35cand a coil compression spring 35d, extends from an armature end 77 ofreset solenoid RS to engage contact member 15 by a loose rocking andresilient connection. Slider plate 35b of linkage or slider assembly 35has an extension 79 (FIG. 108) at its upper end with a T-slot 81 forcoupling engagement with the enlarged end 77 of the armature. Coilcompression spring 35d is nested within a window 83 having opposedtongues 85 projecting from the top and bottom thereof. A laterallyextending actuation tab 87 projects from one edge of slider plate 35b.

Slider plate 35a (FIG. A) has an upwardly extending tongue 89 which,when slider plates 35a and 35b are assembled as shown in FIGS. 11A and11B, is positioned within the coils of spring 3511, the lower end ofthis spring engaging shoulders 88. A tongue 91 projects downwardly fromthe lower end of plate 35a for engagement within slot 71 of contactmember 15. Four bosses 93 are formed in the surface of plate 35a andprovide a reduced friction engagement with the opposing surface of plate35b when assembled. The third slider plate 350 (FIG. 10C) has a tongue95 formed at the top of a window or slot 97. This tongue extendsdownwardly so as to be positioned within the coils of spring 35d whenthe plates are assembled and thus serve as a spring retainer. -Whenreset solenoid RS is energized, the downward thrust of armature end 77is transmitted through the first driving member (slider 35b which isresiliently coupled (by spring 35d) to the second driving member (sliderplate 35a) to drive contact member downwardly. The closing impact of thecontacts is cushioned by spring-35d which maintains substantiallyconstant contact pressure even though the contacts may wear down fromextended usage. As contact member 15 is thus moved from its openposition (FIG. 3) to its closed position (FIG. 4) against' the bias ofspring 37, finger 63 of contact arm end 33 is seated against abutment orlatch catch 29. Sliders 35a and 35b are provided with respectiveelongate slots 99 and 101 which, when these sliders are assembled withslider plate 35c, register with the latters slot 97 and thus provide anelongate opening for passage of contact arm spring 37. Slide assembly 35moves within a pair of opposed guideways 102 and 102' formed on theinner surfaces of the sidewalls of housing H.

When the linkage constituted by slider assembly 35 has moved member 15into its closed position of FIG. 4, latch means LM2 engages to holdslider plate 35b in its downward position. Latch means LM2 includes abell crank lever having an upper arm 103 with a latch hook 105 at itsend for engaging the top edge of slider plate 35b, and a second arm 107from which extends a lateral arm 109 carrying a spring finger 111. Latchmeans LM2 is biased clockwise by spring 41 about a latch pivot pin 113,thereby urging latch hook 105 into engagement with the top edge ofslider plate 35b. Latch means LM2 is moved from its latched (FIG. 4) toits unlatched (FIG. 3) position by firing or energizing trip solenoidTS, which has an armature 115 coupled to latch arm 107 by a connectinglink 117. Energizing solenoid TS moves latch means LM2 counterclockwiseabout its pivot 113 against the bias of spring 41 and thereby releaseslinkage 35, permitting member 15 to move clockwise about its pivot pointon catch 29 and under the contact opening bias of spring 37. Latch arm107 includes an aperture 119 adapted to receive a ganging bar forcrosscoupling adjacent breaker units CB1 for multiphase operation sothat tripping of one breaker CB1 in one phase will trip all of theganged breakers.

It will be noted that spring finger 111will depress and thus actuatelatch switch LS, shown in phantom when latch means LM2 engages the topedge of slider plate 35b upon the contact member 15 reaching its closedposition. Thus switch LS remains in its FIG. 4 actuated position as longas contact member 15 is closed and until the trip solenoid TS is fired.

Under an overload condition, breaker CB1 is tripped by latch means LMlindependently of latch means LM2. If the overload is due to a shortcircuit on an extremely heavy current drawing fault, the electromagnetconstituted by poles 51 and the turns formed by extension 47 willimmediately pull in latch member 25, moving abutment or catch 29 to theright and causing contact member 15 to move to its tripped position(FIG. 5). A relatively low level longer term fault will cause bimetalelement 11 to heat and move its extension 55 to the right, thusactuating latch member 25 similarly to release end 33 of contact member15. As member 15 moves clockwise under the bias of spring 37, it pivotsabout tongue 91 so that the upper surface of the free end of maincontact arm portion 15a moves against the actuator button of overloadswitch OS and depresses it. As discussed above, actuation of switch OS,shown in phantom, energizes or fires trip solenoid TS, thereby releasinglatch means LM2 and allowing slider assembly 35 to move to its FIG. 3position. As slider assembly 35 moves upwardly, opening to the FIG. 11Aexpanded position because of compression spring 35d, contact member 15willpivot first around the actuator button of switch OS as spring 37exerts an upward force on bracket 15c. After initial counterclockwiserotation of contact member 15 around this pivot point, the upperintermediate surface of main contact arm portion 15a will strike a pin121 mounted in housing H. The pivot point then shifts to pin 121, whichserves as a fulcrum as contact member 15 moves to its FIG. 3 positionwith its free end separated from switch OS and'with'its end finger 63poised over catch 29 when the latter returns to its normal coolposition. Thus overload switch OS is only momentarily actuated uponoverload tripping by release of latch LM2. This momentary actuation,however, fires trip solenoid TS, which releases latch LMI and alsocompletes a relatively high current circuit through bimetal 7 of remoteunit RC1 so that push button PBl will pop out to signal tripping of CB1due to an overload. The fault is thereby cleared and both remote unitRC1 and breaker CB1 are prepared for reclosing or resetting when thecurrentsensing thermally responsive latch means LMl has cooled andreturned to its normal position.

Breaker CB1 may be calibrated by adjustment of screw 123 which moves theend of bimetal extension 55 relative to end 33 of arm 53 of latch member25. Once the breaker is calibrated as desired, this calibration will beaccurately maintained over the long operational life of the breakerbecause of the provision of various features of this invention. Thesefeatures include the unique slider linkage assembly 35, the engagementarrangement between tongue 91 in slot 71 and the method of biasingcontact member by spring 37 against latch member 25. Maintenance ofclose tolerance calibration is a function of a number of variables, allof which are taken into account in this breaker structure. The momentarm from the pivot point of finger 63 on catch 29 to the point ofengagement of linkage 35 with the contact member 15 is one suchvariable. This is maintained constant as spring 37 urges contact member15 to the right so that the tip of finger 63 will always be snugly movedinto abutting contact with the left surface of member 25 and fullyengage the top surface of catch 29. Thus catch 29 will always have thesame frictional factor to overcome when it moves to a release positionand the spacing or moment arm between that point and the point ofengagement of tongue 91 and contact member 15 will be maintainedconstant. Therefore, even with the loose rocking engagement between thelatter two components, which can be inexpensive stampings, precisecalibration and very close tolerances can be attained as contact member15 is biased by spring 37 consistently to return to this precisereference position, regardless of wear. Spring 37 also exerts asubstantially constant force biasing the slider plates 35a, 35b and 35ctogether. Further, as discussed above, compression spring 35d maintainsconstant contact force despite possible contact erosion and theresultant changes in the angularity of contact member 15 when closed.

A nonlatch type breaker CB2 as described above in regard to FIG. 2 isfurther illustrated in FIG. 6. Such a breaker may be made fromsubstantially the same components as those used to fabricate breaker CB1and with only minor modifications. These involve changing the shape oflatch hook 105 to that of latch hook 105 wherein the engaging face ofhook 105' is angled slightly upwardly, and inverting solenoid TS so thatit will pull its armature 115 inwardly upon energization rather thanthrusting it outwardly. As the trip solenoid is inverted and the wiringof the latch switch is slightly modified in the CB2 breaker, thesecomponents are indicated at TS and LS, the reference character LM2 beingused to indicate the modified nature of this latch means. Anothermodification involves elimination of spring 41 and the stiffening ofspring 111 of the CB2 breaker, as indicated at 111'. This provides amodest bias from the inherent biasing force of the internal spring inthe microswitch type latch switch LS, which urges this latch LM2 into areleased or unlatched position. As noted above, the trip solenoid ismaintained energized continuously while breaker contact member 15remains closed and will only be deenergized upon intermittent actuationof overload switch 08 during tripping due to overload or by operation inthe contactor mode by remote unit RC2. Only a low level energizationcurrent through trip solenoid TS is required to maintain slider assembly35 latched.

In certain instances it may be desirable to provide for local manualactuation of the circuit breaker CB1 and FIG. 9 illustrates an exemplaryembodiment including this feature. A springloaded push button PB3 ofinsulating material is slidably mounted on housing H and coupled to acam plate 125 by a connecting link 127. Another microswitch S2 similarto latch switch LS and overload switch OS is mounted on housing H andhas an actuator arm 129, the end of which bears against the periphery ofcam plate in the neutral or rest position of this plate (shown in solidlines) and is biased so as to nest in a notch 131 of this plate by theinternal biasing force of microswitch 52 and the spring action of theflexible actuator arm 129. Switch S2 is connected in the circuitry forreset and trip solenoids RS and TS. Thus, when cam plate 125 is moved ineither direction around its pivot 133 from its solid-line rest position,actuator arm 129 is moved to the position indicated to its broken-linepositionto actuate switch S2 and effectively disconnect or disable bothsolenoids so that neither can be actuated from the remote unit RC1.

To manually locally reset or reclose breaker CB1, push button'PB3 ispressed (upwardly as shown in FIG. 9) and tab 87 of slider plate 35b ismoved by an edge of cam plate 125 from its solid-line to itsdouble-dot-dash-line position, thus manually closing the contacts ofbreaker CB1 (FIG. 4). As latch means LM2 is biased to an engagedlatching position by spring 41, its arms 107 and 109 will move fromtheir solidto their double-dot-dash-line positions as shown and pushbutton PB3, when released, will return to its neutral rest positionunder the centering bias of its captive spring 137.

To manually trip breaker CB1, push button PB3 is pulled down (as viewedin FIG. 9) so that cam plate finger 135 will contact and move latch arm109 to its solid-line position and thus disengage latch means LM2 andpermit slider assembly linkage 35 to release and open the breakercontacts, as represented by actuator tab 87 moving to its solid-lineposition. Thus in manual local actuation to either a contacts-open or aclosed-contact position, there is a lost motion connection between PB3and the operating components of breaker CB1, and when cam plate 125 ismoved in either direction from its neutral rest solid-line position,switch S2 will be actuated to deenergize these solenoids to prevent anyinadvertent override by concurrent actuation of remote control unit RC1.

If it should be desired to provide remote indication of the physicalposition of contact member 15, this is provided by a further switch S3secured to housing H and having an actuator arm 139 which engages sliderassembly actuator tab 87. In an open-contact position, tab 87 will be inits solid-line position and switch S3 will not be actuated, but whencontact member 15 is moved to its closed position, tab 87 will move downto its double-dot-dash position and actuator switch S3 which will closea circuit to a remote indicator to signal that the breaker contacts arephysically closed.

It is to be understood that remote control circuitry other than thatspecifically illustrated herein may be utilized for remote control ofthe breakers of this invention. It is also to be noted that latch meansother than LMl (such as one uncompensated for ambient temperaturevariations), LM2 and LM2 are useful in the practice of this invention.

In view of the above, it will be seen that the several objects of theinvention are achieved and other advantageous results attained.

As various changes could be made in the above constructions withoutdeparting from the scope of the invention, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

What is claimed is:

1. A circuit breaker comprising:

a fixed contact;

a movable contact member including a movable contact adapted forengagement with the fixed contact, said member being movable between afirst position in which said contacts are separated and a secondposition in which said contacts are in conductive engagement;

motor means for moving said contact member from its first position toits second position when the motor means is actuated, said means beingactuatable by means remote from said circuit breaker;

condition-sensing latch means for retaining said contact member in itssecond position until the condition sensed varies beyond a predeterminedvalue whereupon said latch means releases said contact member to opensaid contacts independently of the actuation of said motor means; and

further latch means for retaining said contact member in its secondposition, said further latch means being responsive to actuation of saidremote means thereby to release said contact member and separate saidcontacts.

2. A circuit breaker comprising: a fixed contact;

a movable contact member including a movable contact adapted forengagement with the fixed contact, said member being movable between afirst position in which said contacts are separated and a secondposition in which said contacts are in conductive engagement;

means comprising a solenoid and an armature actuated thereby for movingsaid contact member from its first position to its second position whenthe solenoid is energized, said solenoid being energizable by switchmeans remote from said circuit breaker;

current-sensing latch means for retaining said contact member in itssecond position until the current sensed exceeds a predetermined valuewhereupon said latch means releases said contact member to open saidcontacts independently of the energization of said solenoid; and

further latch means for retaining said contact member in its secondposition, said further latch means being responsive to actuation of saidremote switch means thereby to release said contact member and separatesaid contacts.

3. A circuit breaker as set forth in claim 2 which further includesanother solenoid and an armature actuated thereby for causing saidcontact member to move from its second to its first position, the lastsaid solenoid being energizable by said remote switch means.

4. A circuit breaker as set forth in claim 2 further comprising meansresponsive to release of said contact member by said current-sensinglatch means for giving indication of said release at said remote switchmeans.

5. A circuit breaker as set forth in claim 4 wherein said means forgiving indication of release of said contact member comprises furtherswitch means actuatable by movement of the contact arm from its secondto its first position in response to release of the contact arm by saidcurrent-sensing latch means, and an indicator located with said remoteswitch means and responsive to actuation of said further switch means.

6. A circuit breaker as set forth in claim 5 in which said indicatorincludes a thermal motor which is energized by actuation of said furtherswitch means.

7. A circuit breaker as set forth in claim 2 further comprisingadditional switch means for deenergizing the first said solenoid aftersaid contact member is moved into said second position thereby.

8. A circuit breaker as set forth in claim 3 which further comprisesmeans for coupling movement of the first said armature to said contactmember.

9. A circuit breaker as set forth in claim 8 wherein said further latchmeans is adapted for engagement with the means for coupling movement tosaid contact member, and which includes means for coupling movement ofthe armature of said further solenoid to said further latch, saidfurther solenoid being responsive to said remote switch means to releasesaid further latch means and permit said contact member to return to itsfirst position.

10. A circuit breaker as set forth in claim 9 wherein said further latchmeans is spring-biased into engagement with the noid.

11. A circuit breaker as set forth in claim 9 wherein said further latchmeans is held in engagement with the means coupling movement to saidcontact member by continued energization of said further solenoid and isreleased from engagementby deener ization of the further solenoid.

2. A circuit brea er as set forth in claim 2 which further includesmanual means adapted to move said contact member to its second positionand alternatively to move said further latch means to release saidcontact member from its second position and permit it to return to itsfirst position, said manual means having a lost motion connection withsaid further latch means and a lost motion connection with said contactmember.

13. A circuit breaker as set forth in claim 12, said manual means havinga neutral rest position in which it is not in engagement with saidcontact member or said further latch means, said breaker furtherincluding another switch means adapted to be actuated when said manualmeans is moved from its neutral rest position thereby to disconnect saidremote switch means from said solenoid.

14. A circuit breaker as set forth in claim 2 which includes means forganging its further latch means to the further latch means of at leastone additional like breaker for multiphase operation whereby the releaseof one of the further latch means releases all of said ganged latchmeans.

15. A circuit breaker comprising: a fixed contact;

a movable contact member including a movable contact adapted forengagement with the fixed contact, said member being movable between afirst position in which said contacts are separated and a secondposition in which said contacts are in conductive engagement;

motor means for moving said contact member from its first position toits second position when the motor means is actuated, said means beingactuatable by means remote from said circuit breaker;

condition-sensing latch means for retaining said contact member in itssecond position until the condition sensed varies beyond a predeterminedvalue whereupon said latch means releases said contact member to opensaid contacts independently of the energization of said motor means; and

another motor means actuated thereby for causing the contact member tomove from its second to its first position, the last said means beingactuatable by said remote switching means.

16. A circuit breaker comprising: a fixed contact;

a movable contact member including a movable contact adapted forengagement with the fixed contact, said member being movable between afirst position in which said contacts are separated and a secondposition in which said contacts are in conductive engagement;

means comprising a solenoid and an armature actuated thereby for movingsaid contact member from its first position to its second position whenthe solenoid is energized, said solenoid being energizable by switchmeans remote from said circuit breaker;

current-sensing latch means for retaining said contact member in itssecond position until the current sensed exceeds a predetermined valuewhereupon said latch means releases said contact member to open saidcontacts independently of the energization of said solenoid; and

another solenoid and an armature actuated thereby for causing thecontact member to move from its second to its first position, the lastsaid solenoid being energizable by said remote switch means.

1. A circuit breaker comprising: a fixed contact; a movable contactmember including a movable contact adapted for engagement with the fixedcontact, said member being movable between a first position in whichsaid contacts are separated and a second position in which said contactsare in conductive engagement; motor means for moving said contact memberfrom its first position to its second position when the motor means isactuated, said means being actuatable by means remote from said circuitbreaker; condition-sensing latch means for retaining said contact memberin its second position until the condition sensed varies beyond apredetermined value whereupon said latch means releases said contactmember to open said contacts independently of the actuation of saidmotor means; and further latch means for retaining said contact memberin its second position, said further latch means being responsive toactuation of said remote means thereby to release said contact memberand separate said contacts.
 2. A circuit breaker comprising: a fixedcontact; a movable contact member including a movable contact adaptedfor engagement with the fixed contact, said member being movable betweena first position in which said contacts are separated and a secondposition in which said contacts are in conductive engagement; meanscomprising a solenoid and an armature actuated thereby for moving saidcontact member from its first position to its second position when thesolenoid is energized, said solenoid being energizable by switch meansremote from said circuit breaker; current-sensing latch means forretaining said contact member in its second position until the currentsensed exceeds a predetermined value whereupon said latch means releasessaid contact member to open said contacts independently of theenergization of said solenoid; and further latch means for retainingsaid contact member in its second position, said further latch meansbeing responsive to actuation of said remote switch means thereby torelease said contact member and separate said contacts.
 3. A circuitbreaker as set forth in claim 2 which further includes another solenoidand an armature actuated thereby for causing said contact member to movefrom its second to its first position, the last said solenoid beingenergizable by said remote switch means.
 4. A circuit breaker as setforth in claim 2 further comprising means responsive to release of saidcontact member by said current-sensing latch means for giving indicationof said release at said remote switch means.
 5. A circuit breaker as setforth in claim 4 wherein said means for giving indication of release ofsaid contact member comprises further switch means actuatable bymovement of the contact arm from its second to its first position inresponse to release of the contact arm by said current-sensing latchmeans, and an indicator located with said remote switch means andresponsive to actuation of said further switch means.
 6. A circuitbreaker as set forth in claim 5 in which said indicator includes athermal motor which is energized by actuation of said further switchmeans.
 7. A circuit breaker as set forth in claim 2 further comprisingadditional switch means for deenergizing the first said solenoid aftersaid contact member is moved into said second position thereby.
 8. Acircuit breaker as set forth in claim 3 which further comprises meansfor coupling movement of the first said armature to said contact member.9. A circuit breaker as set forth in claim 8 wherein said further latchmeans is adapted for engagement with the means for coupling movement tosaid contact member, and whIch includes means for coupling movement ofthe armature of said further solenoid to said further latch, saidfurther solenoid being responsive to said remote switch means to releasesaid further latch means and permit said contact member to return to itsfirst position.
 10. A circuit breaker as set forth in claim 9 whereinsaid further latch means is spring-biased into engagement with the meanscoupling movement to said contact member and is released from engagementby energization of the further solenoid.
 11. A circuit breaker as setforth in claim 9 wherein said further latch means is held in engagementwith the means coupling movement to said contact member by continuedenergization of said further solenoid and is released from engagement bydeenergization of the further solenoid.
 12. A circuit breaker as setforth in claim 2 which further includes manual means adapted to movesaid contact member to its second position and alternatively to movesaid further latch means to release said contact member from its secondposition and permit it to return to its first position, said manualmeans having a lost motion connection with said further latch means anda lost motion connection with said contact member.
 13. A circuit breakeras set forth in claim 12, said manual means having a neutral restposition in which it is not in engagement with said contact member orsaid further latch means, said breaker further including another switchmeans adapted to be actuated when said manual means is moved from itsneutral rest position thereby to disconnect said remote switch meansfrom said solenoid.
 14. A circuit breaker as set forth in claim 2 whichincludes means for ganging its further latch means to the further latchmeans of at least one additional like breaker for multiphase operationwhereby the release of one of the further latch means releases all ofsaid ganged latch means.
 15. A circuit breaker comprising: a fixedcontact; a movable contact member including a movable contact adaptedfor engagement with the fixed contact, said member being movable betweena first position in which said contacts are separated and a secondposition in which said contacts are in conductive engagement; motormeans for moving said contact member from its first position to itssecond position when the motor means is actuated, said means beingactuatable by means remote from said circuit breaker; condition-sensinglatch means for retaining said contact member in its second positionuntil the condition sensed varies beyond a predetermined value whereuponsaid latch means releases said contact member to open said contactsindependently of the energization of said motor means; and another motormeans actuated thereby for causing the contact member to move from itssecond to its first position, the last said means being actuatable bysaid remote switching means.
 16. A circuit breaker comprising: a fixedcontact; a movable contact member including a movable contact adaptedfor engagement with the fixed contact, said member being movable betweena first position in which said contacts are separated and a secondposition in which said contacts are in conductive engagement; meanscomprising a solenoid and an armature actuated thereby for moving saidcontact member from its first position to its second position when thesolenoid is energized, said solenoid being energizable by switch meansremote from said circuit breaker; current-sensing latch means forretaining said contact member in its second position until the currentsensed exceeds a predetermined value whereupon said latch means releasessaid contact member to open said contacts independently of theenergization of said solenoid; and another solenoid and an armatureactuated thereby for causing the contact member to move from its secondto its first position, the last said solenoid being energizable by saidremote switch means.